1. Field of the Disclosure
The present disclosure relates to a clipping tool for clipping a component and particularly, but not exclusively to a clipping tool for clipping a forged component such as a gas turbine aerofoil body.
2. Description of the Related Art
Metal components are forged by applying compressive loads to form the metal into the desired shape. This is conventionally achieved by placing the metal between two dies which are forced together such that the metal forms into the interior profile of the dies. In doing so, metal is often forced through the interface of the two dies, the parting line, creating a burr around the component, known as flash. The flash can be removed by a subsequent clipping or trimming process.
Conventionally, clipping processes use a clipping die to hold a component as it is forced through clipping steels having an aperture sized to the desired final shape of the component. The component is placed on top of the die so that the flash extends outside. The component is then forced through the opening in the clipping steels by a punch causing the flash extending outside the dies to be sheared from the component.
A clipping process is shown in FIGS. 1 and 2 for clipping components having an aerofoil surface, such as a compressor stator vanes or blades. The process uses a clipping die 2, as shown in FIG. 1, having a riser 4 and a base 6. The riser 4 comprises a support surface 8 for supporting the component above the base 6.
The riser 4 further comprises referencing members 12 disposed at opposing ends of the riser 4 adjacent to the support surface 8. A recess 14 is provided for receiving a root portion of the component.
As shown in FIG. 2, the riser 4 is located accurately within a tool body formed by a pair of clipping steels 16 (only one shown for diagrammatical purposes), one at each side of the riser 4. The riser 4 and base 6 are mounted on a hydraulic cylinder which provides a reaction force to counteract the force of a punch (not shown). The punch is driven down under hydraulic power to clamp the component on the riser 4 and drive the punch, component and riser 4 down through the clipping steels 16. As the punch, component and riser 4 pass through the clipping steels 16, flash is sheared off between the edges of the punch and the clipping steels 16.
This conventional process has been found to be effective where the flash has a thickness of less than around 1 mm. However, where the flash has a greater thickness, the edge cut by the clipping steels as the punch, component and riser 4 pass though the aperture in the clipping steels exhibits undesirable smearing. As a result, such an edge typically requires post-clipping machining in order to obtain the required geometry and edge surface finish.
Where the component is an aerofoil body for a gas turbine, the flash associated with the leading and trailing edges of the body are typically less than 1 mm and this can be effectively clipped using the known clipping tools. However, the flash associated with the tang portions at the opposing lateral ends of the aerofoil body is typically thicker e.g. around 3.5 mm and thus the tang portions are typically subjected to post-clipping machining to obtain the required tang geometry.
Post-clipping machining increases the cost and time scales of production of components. Furthermore, clipping of flash having an increased thickness leads to increased clipping tool wear.